Worcester Bosch Sensor Calibration / Communication Error

Boiler shows D1 and may continue to run at reduced performance.

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

Possible Causes

Faulty temperature sensor, Loose harness connection, PCB firmware issue, Electrical interference on sensor lines

Safety first: Isolate power before handling internal components.

Reset boiler: Perform a reset and monitor operation. If D1 persists, further checks are needed.
Check wiring harness: Inspect sensor harnesses for damage, corrosion, or loose plugs at the PCB.
Engineer tasks: A professional may need to update PCB firmware (if applicable), replace suspect sensors, or replace the PCB if communication errors cannot be resolved.

Hard 4/5

Main Control PCB

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